The present invention realtes to an ink fountain incorporating individually regulated metering segments, for a printing machine.
Ink fountains for printing machines are already known, which comprise a vat containing ink, this vat being defined, on one side, by a horizontal inking roller driven in rotation, on the opposite side, by a body extending parallel to the inking roller, and laterally, by two vertical cheeks. The body bears, in the immediate vicinity of the peripheral surface of the inking roller, a doctor blade parallel to the inking roller and which is formed by a succession of metering segments adjacent one another, and of which the front faces are defined, on the inking roller side, by wiping edges which extend parallel to the inking roller, at a short distance from the peripheral surface thereof, this distance being adapted to be adjusted individually for each metering segment. The end parts of the metering segments which are opposite the front faces bearing the wiping edges are fixed to the body of the ink fountain. The metering segments are actuated individually by pusher members extending through the body and which are controlled, for example, by adjusting levers or motorized assemblies. Each of these pusher members exerts a thrust on the mobile end part of the metering segment which is associated therewith. In this way, it is possible, with the aid of these pusher members, to place the wiping edge of each individual metering segment more or less close to the peripheral surface of the inking roller and thus to adjust the thickness of the film of ink passing between the wiping edge of the metering segment in question and the peripheral surface of the inking roller. Such an ink fountain is described for example in French Patent Application No. 83 01945, which corresponds to U.S. Pat. No. 4,479,434.
Due to the improved performances in inking, a continuous ink-intake system has been developed which necessitates thicknesses of the film of ink (of the order of 0.3 mm) smaller than with the conventional system employing an oscillating intake roller. This small thickness must be able to vary from 0 to 100% as a function of the conditions necessary for inking. In addition, the modern remote-control and servo-control systems themselves necessitate high-precision to make it possible to return to the same initial conditions. Certain known embodiments employ a lever which multiplies the movement between a pusher member and the segment that it controls. In a known solution of this type, such as that described in German Pat. No. 3 047 689, each metering segment forms a lever of the first type comprising a first lever arm, of short length, between the wiping edge of the metering segment and the pivot axis thereof, and a second lever arm, of long length, between the point of application of the effort of the pusher member on the metering segment and the pivot axis.
Heretofore known ink fountains of this type present numerous drawbacks such as the risk of penetration of the ink between the metering segments and between them and the common support unit or the pusher members. Seals are placed at certain points wherever possible, but without being able to avoid such penetration by clearances between the metering segments. This ink in a thin layer dries, soils and prevents operation of the ink fountain under good conditions, rendering maintenance thereof very difficult.